Multi-ply wiping products made according to a low temperature delamination process

ABSTRACT

The present invention is generally directed to paper products having great softness and strength. The paper products are formed from one or more paper webs that can be made according to various methods. In one embodiment, the paper web is an uncreped through-air dried web. The web can contain softwood fibers in combination with high-yield fibers. For example, the high-yield fibers can be contained in the middle layer of a stratified fiber furnish. In accordance with the present invention, a first bonding material is applied to a first side of the web and optionally a second bonding material is applied to a second side of the paper web. The bonding materials are applied according to preselected patterns. At least one side of the paper web is creped after one of the bonding materials is applied. The bonding material applied to the creped side of the web can be an adhesive selected that allows the web to be creped at relatively low temperatures.

RELATED APPLICATIONS

The present application is a Continuation-in-Part application to U.S.patent application Ser. No. 10/192,781, filed on Jul. 10, 2002 now U.S.Pat. NO. 6,846,383.

BACKGROUND OF THE INVENTION

Absorbent paper products such as paper towels, facial tissues and othersimilar products are designed to include several important properties.For example, the products should have good bulk, a soft feel and shouldbe highly absorbent. The product should also have good strength evenwhile wet and should resist tearing. Unfortunately, it is very difficultto produce a high strength paper product that is also soft and highlyabsorbent. Usually, when steps are taken to increase one property of theproduct, other characteristics of the product are adversely affected.For instance, softness is typically increased by decreasing or reducingfiber bonding within the paper product. Inhibiting or reducing fiberbonding, however, adversely affects the strength of the paper web.

One particular process that has proved to be very successful inproducing paper towels and wipers is disclosed in U.S. Pat. No.3,879,257 to Gentile, et al., which is incorporated herein by referencein its entirety. In Gentile, et al., a process is disclosed in which abonding material is applied in a fine, spaced apart pattern to one sideof a fibrous web. The web is then adhered to a heated creping surfaceand creped from the surface. A bonding material is applied to theopposite side of the web and the web is similarly creped. The processdisclosed in Gentile, et al. produces wiper products having exceptionalbulk, outstanding softness and good absorbency. The surface regions ofthe web also provide excellent strength, abrasion resistance, andwipe-dry properties.

Although the process and products disclosed in Gentile, et al. haveprovided many advances in the art of making paper wiping products,further improvements in various aspects of paper wiping products remaindesired. For example, many commercially available adhesives that may beused in the process disclosed in Gentile, et al. require that the paperproduct be placed on a heated creping surface prior to being creped fromthe surface. Further, in order for the adhesives to be subjected to asufficient amount of heat, the paper must remain on a heated crepingsurface for an extended period of time requiring the creping drum tohave a relatively large diameter. Thus, many conventional print bondedcreping processes have high energy requirements.

In view of the above, a need exists for a print creping process thatrequires less energy in producing a product, such as a multi-ply paperproduct. In particular, it is believed that the process can be made muchmore economical if an adhesive can be selected that has lowertemperature requirements during creping. Further, a need also exists fora single creped product that has improved properties andcharacteristics. For instance, a need exists for a creped product thathas improved bulk characteristics in comparison to many conventionalprint bonded creping products.

SUMMARY OF THE INVENTION

In general, the present invention is directed to a method for producingpaper products and to paper products made from the method. The paperproducts can be, for instance, paper towels, industrial wipers, facialtissues, bath tissues, napkins, and the like. The process includes thesteps of providing a paper web containing papermaking fibers. A firstbonding material is applied to a first side of the web in a preselectedpattern. The first side of the web is then adhered to a creping surfaceat a temperature of greater than about 50° F. and less than about 200°F. More particularly, the temperature of the creping surface is lessthan about 150° F., and in one embodiment is at ambient temperatures.Once adhered to the creping surface, the first side of the web is crepedfrom the creping surface using a creping blade.

Once the first side of the web is creped, in one embodiment, the web maybe combined with one or more other webs to form a multiple ply product.In general, the second side of the web, which may be bondingmaterial-free and uncreped, is laminated or otherwise attached to asecond paper web in order to form the multiple ply product.

When forming a multiple ply product according to the present invention,the second nonwoven web may be made in a manner similar to the firstnonwoven web. For instance, the second nonwoven web can also containpaper-making fibers and can have a first bonding material applied to afirst side of the web. The first side of the web may be subjected to acreping process. When forming a two-ply product, the second side of thefirst paper web may be attached to the second side of the second paperweb. In this manner, the creped sides of the webs form the exteriorsurfaces of the paper product.

As described above, when creping the first side of each web, the web maybe adhered to a creping surface at a temperature of less than about 200°F. Thus, in one embodiment, the present invention is generally directedto a print creping process that can occur at relatively lowertemperatures. Further, since the creping adhesive used in the presentinvention does not require relatively large amounts of heat in order tobond to a creping surface, the paper product treated in accordance withthe present invention can remain on a creping surface for a period oftime much shorter in duration than many conventional processes. As such,the creping drum in the process of the present invention can have asmaller diameter than many drums used in the past in similar processes.

The papermaking fibers used to construct the paper webs of the presentinvention can vary depending on the particular application. Forinstance, hardwood and softwood fibers can be used. In one embodiment,the paper webs can also include high-yield fibers, such asthermomechanical pulp. The high-yield fibers can be present in a web inan amount from about 5% to about 40% by weight. In one embodiment, apaper web may be used containing multiple layers. The web can include amiddle layer containing the high-yield fibers either alone or incombination with other fibers such as softwood fibers and/or hardwoodfibers. The outer layers can also contain softwood fibers.

The paper webs that are treated in accordance with the present inventioncan be made according to different processes. For example, the web canbe a wet-creped base sheet or an uncreped through-air dried base sheet.Each paper web can have a basis weight of from about 15 gsm to about 110gsm, and particularly from about 35 gsm to about 70 gsm. When formingmultiple ply products, however, the basis weight of each nonwoven webmay be from about 15 gsm to about

55 gsm, and particularly from about 20 gsm to about 40 gsm. Besidesdifferent types of fibers, the webs can also contain a debonding agent.For example, a debonding agent can be present in the web in an amountfrom about 1 kg per metric tonne to about 6 kg per metric tonne basedupon the total weight of fibers contained in the web.

In one embodiment, a bonding material is only applied to one side of theweb in a pre-selected pattern. Applying the bonding material to one sideof the web is particularly well suited for processes used to formmultiple ply products. In other embodiments, however, a first bondingmaterial is applied to the first side of the web in a preselectedpattern, while a second bonding material is applied to the second sideof the web in a preselected pattern. Treating the web on each side withbonding materials is particularly well suited in the construction of asingle ply product. The first and second bonding materials can be thesame materials or can be different bonding materials. Further, thepatterns that are used to apply the bonding materials can be the same ordifferent. For example, the patterns can be reticulated patterns or canbe patterns that comprise a succession of discrete shapes.

In general, the bonding material can be applied to the wiping product,whether the product is a single ply product or a multiple ply product,in an amount of from about 2% to about 25% by weight of the paper web,particularly about 4% to about 10% by weight, and more particularly fromabout 6% to about 8% by weight of the web.

In one embodiment, the bonding material can be applied to the paper webin a pattern that comprises a succession of discrete shapes. Forinstance, the bonding material can be applied to the first side of thepaper web in a pattern that comprises a succession of discrete dots. Inanother embodiment, the bonding material may be applied to the web in apattern that comprises a succession of, for instance, hexagons. Thepattern applied to the web can cover from about 25% to about 75% of thesurface area of one side of the web, and particularly from about 40% toabout 60% of the surface area of one side of the web.

In accordance with the present invention, the bonding material that isapplied to the web is a bonding material that will adhere to a crepingsurface at relatively low temperatures, such as less than about 150° F.The bonding material can have a glass transition temperature of fromabout 10° C. to about −20° C.

The web, which may be a through-air dried web, can also undergo rushtransfer between two web conveying devices in the papermaking line, suchas between a first fabric and a second moving fabric prior to applyingthe bonding material. The second fabric can be downstream from the firstfabric and can move at a speed that is about 5% to about 45% slower thanthe first fabric.

Through the process of the present invention, various paper products canbe formed. The paper products can be single-ply or multi-ply productsthat can be used in various wiping applications.

When forming multiple ply products, the different plies can be attachedusing any suitable method. For instance, in one embodiment, an adhesivecan be applied in between the different plies of the product. After theplies are attached, the paper product can be calendered and/or embossedif desired.

Other features and aspects of the present invention are discussed ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one of ordinary skill in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures in which:

FIG. 1 is a schematic diagram of a paper web forming machine,illustrating the formation of a stratified paper web having multiplelayers in accordance with the present invention;

FIG. 2 is a schematic diagram of one embodiment of a process for forminguncreped through-dried paper webs for use in the present invention;

FIG. 3 is a schematic diagram of one embodiment of a process for formingwet creped paper webs for use in the present invention;

FIG. 4 is a schematic diagram of one embodiment of a process forapplying bonding materials to each side of a paper web and creping oneside of the web in accordance with the present invention;

FIG. 5 is a plan view of one embodiment of a pattern that is used toapply bonding materials to paper webs made in accordance with thepresent invention;

FIG. 6 is another embodiment of a pattern that is used to apply bondingmaterials to paper webs in accordance with the present invention;

FIG. 7 is a plan view of another alternative embodiment of a patternthat is used to apply bonding materials to paper webs in accordance withthe present invention;

FIG. 8 is a schematic diagram of an alternative embodiment of a processfor applying a bonding material to one side of the paper web and crepingone side of the web in accordance with the present invention;

FIG. 9 is a plan view of one embodiment of a process for laminatingpaper webs together in accordance with the present invention; and

FIG. 10 is a plan view of an alternative embodiment of a process forlaminating paper webs together in accordance with the present invention.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the present invention.

DETAILED DESCRIPTION

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstruction.

In general, the present invention is directed to a process for producingpaper wiping products having great softness and strengthcharacteristics. In particular, the wiping products have high strengthvalues when either dry or wet. Further, the products have good stretchcharacteristics and are tear resistant. The products also have anincreased sheet caliper, and increased bulk.

The process of the present invention generally involves applying a firstbonding material to a first side of a base sheet or paper web.Optionally, a second bonding material, which can be the same ordifferent from the first bonding material, may be applied according to apreselected pattern to the second side of the paper web. The first sideof the paper web is then adhered to a creping surface and creped fromthe surface.

In accordance with the present invention, the first bonding materialused in the present invention is a bonding material that will adhere toa creping surface at a relatively low temperature. For instance, duringthe creping process, the creping surface can be heated to a temperatureof less than about 200° F., particularly at a temperature of less thanabout 150° F. and more particularly at a temperature of less than about125° F. In one embodiment, for instance, the creping surface can be atambient temperatures.

Many advantages and benefits can be realized when using a crepingadhesive that has relatively low temperature requirements. For instance,the total energy requirements of the process are significantly reduced.Further, when using a low temperature creping adhesive, the web need notremain on the creping surface for any extended period of time. As such,the size of the creping drum can be reduced and/or the web can remain onthe creping drum for a relatively short period of time. For example, theweb can remain on the creping drum for a period of less than about 0.3seconds, particularly for a period of less than about 0.25 seconds andmore particularly for a period of less than about 0.22 seconds. Byshortening the amount of time the paper is required to be on the crepingdrum, the process becomes faster and more efficient and capable ofproducing more product per unit time.

The first bonding material can have a glass transition temperature ofless than about 10° C., particularly less than about −5° C., and moreparticularly can have a glass transition temperature of from about 10°C. to about −20° C.

In accordance with the present invention, the bonding materials areapplied to the paper web in preselected patterns for providing strengthand stretchability. Creping the web, on the other hand, causesdelamination and increases the sheet caliper and cross-directionalstretch of the web. By increasing caliper, creping also increases thebulk of the sheet making the paper web feel softer.

Paper webs made in accordance with the present invention may be used insingle ply paper products or in multiple ply paper products. In oneembodiment, for instance, two paper webs made according to the presentinvention can be laminated together in forming a two-ply product. Thecreped side of each web can form the exterior surfaces of the paperproduct. When forming a two-ply product, a bonding material, in oneembodiment, may be applied only to one side of each ply. The untreatedand uncreped sides of each ply are then adhered together to form themultiple ply product.

Paper webs processed according to the present invention can be made indifferent manners and can contain various different types of fibers. Ingeneral, however, the paper web contains papermaking fibers, such assoftwood fibers. In addition to softwood fibers, the paper web can alsocontain hardwood fibers such as eucalyptus fibers and/or high-yield pulpfibers.

As used herein, “high-yield pulp fibers” are those papermaking fibersproduced by pulping processes providing a yield of about 65 percent orgreater, more specifically about 75 percent or greater, and still morespecifically from about 75 to about 95 percent. Yield is the resultingamount of processed fiber expressed as a percentage of the initial woodmass. Such pulping processes include bleached chemithermomechanical pulp(BCTMP), chemithermomechanical pulp (CTMP) pressure/pressurethermomechanical pulp (PTMP), thermomechanical pulp (TMP),thermomechanical chemical pulp (TMCP), high-yield sulfite pulps, andhigh-yield kraft pulps, all of which leave the resulting fibers withhigh levels of lignin. High-yield fibers are well known for theirstiffness (in both dry and wet states) relative to typical chemicallypulped fibers. The cell wall of kraft and other non-high-yield fiberstends to be more flexible because lignin, the “mortar” or “glue” on andin part of the cell wall, has been largely removed. Lignin is alsononswelling in water and hydrophobic, and resists the softening effectof water on the fiber, maintaining the stiffness of the cell wall inwetted high-yield fibers relative to kraft fibers. The preferredhigh-yield pulp fibers can also be characterized by being comprised ofcomparatively whole, relatively undamaged fibers, high freeness (250Canadian Standard Freeness (CSF) or greater, more specifically 350 CFSor greater, and still more specifically 400 CFS or greater), and lowfines content (less than 25 percent, more specifically less than 20percent, still more specifically less that 15 percent, and still morespecifically less than 10 percent by the Britt jar test).

In one embodiment of the present invention, the paper web containssoftwood fibers in combination with high-yield pulp fibers, particularlyBCTMP fibers. BCTMP fibers can be added to the web in order to increasethe bulk and caliper of the web, while also reducing the cost of theweb.

The amount of high-yield pulp fibers present in the sheet can varydepending upon the particular application. For instance, the high-yieldpulp fibers can be present in an amount of about 2 dry weight percent orgreater, particularly about 15 dry weight percent or greater, and moreparticularly from about 5 dry weight percent to about 40 dry weightpercent, based upon the total weight of fibers present within the web.

In one embodiment, the paper web can be formed from multiple layers of afiber furnish. The paper web can be produced, for instance, from astratified headbox. Layered structures produced by any means known inthe art are within the scope of the present invention, including thosedisclosed in U.S. Pat. No. 5,494,554 to Edwards, et al., which isincorporated herein by reference.

In one embodiment, for instance, a layered or stratified web is formedthat contains high-yield pulp fibers in the center. Because high-yieldpulp fibers are generally less soft than other papermaking fibers, insome applications, it is advantageous to incorporate them into themiddle of the paper web, such as by being placed in the center of a3-layered sheet. The outer layers of the sheet can then be made fromsoftwood fibers and/or hardwood fibers.

For example, in one particular embodiment of the present invention, thepaper web contains outer layers made from softwood fibers. Each outerlayer can comprise from about 15% to about 40% by weight of the web andparticularly can comprise about 25% by weight of the web. The middlelayer, however, can comprise from about 40% to about 60% by weight ofthe web, and particularly about 50% by weight of the web. The middlelayer can contain a mixture of softwood fibers and BCTMP fibers. TheBCTMP fibers can be present in the middle layer in an amount from about40% to about 60% by weight of the middle layer, and particularly in anamount of about 50% by weight of the middle layer.

In another embodiment of the present invention, the paper web can bemade containing two layers of fibers. The first layer can contain thehigh-yield pulp fibers. The second layer, on the other hand, cancomprise softwood fibers. This particular embodiment is well suited forcreating two-ply products. In particular, the layer of fibers containingthe high-yield fibers can be laminated to a second nonwoven web informing the multi-ply product. The layer of fibers containing thesoftwood fibers, on the other hand, may be treated with a bondingmaterial and creped from a creping surface.

The paper web of the present invention can also be formed without asubstantial amount of inner fiber-to-fiber bond strength. In thisregard, the fiber furnish used to form the base web can be treated witha chemical debonding agent. The debonding agent can be added to thefiber slurry during the pulping process or can be added directly intothe head box. Suitable debonding agents that may be used in the presentinvention include cationic debonding agents such as fatty dialkylquaternary amine salts, mono fatty alkyl tertiary amine salts, primaryamine salts, imidazoline quaternary salts, silicone quaternary salt andunsaturated fatty alkyl amine salts. Other suitable debonding agents aredisclosed in U.S. Pat. No. 5,529,665 to Kaun which is incorporatedherein by reference. In particular, Kaun discloses the use of cationicsilicone compositions as debonding agents.

In one embodiment, the debonding agent used in the process of thepresent invention is an organic quaternary ammonium chloride andparticularly a silicone based amine salt of a quaternary ammoniumchloride. For example, the debonding agent can be PROSOFT TQ1003marketed by the Hercules Corporation. The debonding agent can be addedto the fiber slurry in an amount of from about 1 kg per metric tonne toabout 10 kg per metric tonne of fibers present within the slurry.

In an alternative embodiment, the debonding agent can be animidazoline-based agent. The imidazoline-based debonding agent can beobtained, for instance, from the Witco Corp. The imidazoline-baseddebonding agent can be added in an amount of between 2.0 to about 15 kgper metric tonne.

In one embodiment, the debonding agent can be added to the fiber furnishaccording to a process as disclosed in PCT Application having anInternational Publication No. WO 99/34057 filed on Dec. 17, 1998 or inPCT Published Application having an International Publication No. WO00/66835 filed on Apr. 28, 2000, which are both incorporated herein byreference. In the above publications, a process is disclosed in which achemical additive, such as a debonding agent, is adsorbed ontocellulosic papermaking fibers at high levels. The process includes thesteps of treating a fiber slurry with an excess of the chemicaladditive, allowing sufficient residence time for adsorption to occur,filtering the slurry to remove unadsorbed chemical additives, andredispursing the filtered pulp with fresh water prior to forming anonwoven web.

Referring to FIG. 1, one embodiment of a device for forming amulti-layered stratified pulp furnish is illustrated. As shown, athree-layered head box generally 10 includes an upper head box wall 12and a lower head box wall 14. Head box 10 further includes a firstdivider 16 and a second divider 18, which separate three fiber stocklayers.

Each of the fiber layers comprise a dilute aqueous suspension ofpapermaking fibers. In one embodiment, for instance, middle layer 20contains southern softwood kraft fibers either alone or in combinationwith other fibers such as high yield fibers. Outer layers 22 and 24, onthe other hand, contain softwood fibers, such as northern softwoodkraft.

An endless traveling forming fabric 26, suitably supported and driven byrolls 28 and 30, receives the layered papermaking stock issuing fromhead box 10. Once retained on fabric 26, the layered fiber suspensionpasses water through the fabric as shown by the arrows 32. Water removalis achieved by combinations of gravity, centrifugal force and vacuumsuction depending on the forming configuration.

Forming multi-layered paper webs is also described and disclosed in U.S.Pat. No. 5,129,988 to Farrington, Jr., which is incorporated herein byreference.

The basis weight of paper webs used in the process of the presentinvention can vary depending upon the final product. For example, theprocess of the present invention can be used to produce tissue webs,paper towels, industrial wipers, and the like. For these products, thebasis weight of the paper web can vary from about

15 gsm to about 110 gsm, and particularly from about 35 gsm to about 70gsm. In one particular embodiment, it has been discovered that thepresent invention is particularly well suited for the production ofwiping products having a basis weight of from about 53 gsm to about 63gsm.

In multiple ply products, the basis weight of each paper web present inthe product can also vary. In general, the total basis weight of amultiple ply product will generally be the same as indicated above, suchas from about 20 gsm to about 110 gsm. Thus, the basis weight of eachply can be from about 10 gsm to about 60 gsm, such as from about 20 gsmto about 40 gsm.

As stated above, the manner in which the paper web is formed can alsovary depending upon the particular application. In general, the paperweb can be formed by any of a variety of papermaking processes known inthe art. For example, the paper web can be a wet-creped web, acalendered web, an embossed web, a through-air dried web, a crepedthrough-air dried web, an uncreped through-air dried web, as wellvarious combinations of the above. In one particular embodiment of thepresent invention, however, the paper web is made in an uncrepedthrough-air dried process. It has been discovered that uncrepedthrough-air dried webs provide particular advantages when used in theprocess of the present invention.

For example, referring to FIG. 2, shown is a method for makingthroughdried paper sheets in accordance with this invention. (Forsimplicity, the various tensioning rolls schematically used to definethe several fabric runs are shown but not numbered. It will beappreciated that variations from the apparatus and method illustrated inFIG. 2 can be made without departing from the scope of the invention).Shown is a twin wire former having a papermaking headbox 34, such as alayered headbox, which injects or deposits a stream 36 of an aqueoussuspension of papermaking fibers onto the forming fabric 38 positionedon a forming roll 39. The forming fabric serves to support and carry thenewly-formed wet web downstream in the process as the web is partiallydewatered to a consistency of about 10 dry weight percent. Additionaldewatering of the wet web can be carried out, such as by vacuum suction,while the wet web is supported by the forming fabric.

The wet web is then transferred from the forming fabric to a transferfabric 40. In one embodiment, the transfer fabric can be traveling at aslower speed than the forming fabric in order to impart increasedstretch into the web. This is commonly referred to as a “rush” transfer.Preferably the transfer fabric can have a void volume that is equal toor less than that of the forming fabric. The relative speed differencebetween the two fabrics can be from 0-60 percent, more specifically fromabout 15-45 percent. Transfer is preferably carried out with theassistance of a vacuum shoe 42 such that the forming fabric and thetransfer fabric simultaneously converge and diverge at the leading edgeof the vacuum slot.

The web is then transferred from the transfer fabric to thethroughdrying fabric 44 with the aid of a vacuum transfer roll 46 or avacuum transfer shoe, optionally again using a fixed gap transfer aspreviously described. The throughdrying fabric can be traveling at aboutthe same speed or a different speed relative to the transfer fabric. Ifdesired, the throughdrying fabric can be run at a slower speed tofurther enhance stretch. Transfer can be carried out with vacuumassistance to ensure deformation of the sheet to conform to thethroughdrying fabric, thus yielding desired bulk and appearance ifdesired. Suitable throughdrying fabrics are described in U.S. Pat. No.5,429,686 issued to Kai F. Chiu et al. and U.S. Pat. No. 5,672,248 toWendt, et al. which are incorporated by reference.

In one embodiment, the throughdrying fabric contains high and longimpression knuckles. For example, the throughdrying fabric can haveabout from about 5 to about 300 impression knuckles per square inchwhich are raised at least about 0.005 inches above the plane of thefabric. During drying, the web can be macroscopically arranged toconform to the surface of the throughdrying fabric and form athree-dimensional surface. Flat surfaces, however, can also be used inthe present invention.

The side of the web contacting the throughdrying fabric is typicallyreferred to as the “fabric side” of the paper web. The fabric side ofthe paper web, as described above, may have a shape that conforms to thesurface of the throughdrying fabric after the fabric is dried in thethroughdryer. The opposite side of the paper web, on the other hand, istypically referred to as the “air side”. The air side of the web istypically smoother than the fabric side during normal throughdryingprocesses.

The level of vacuum used for the web transfers can be from about 3 toabout 15 inches of mercury (75 to about 380 millimeters of mercury),preferably about 5 inches (125 millimeters) of mercury. The vacuum shoe(negative pressure) can be supplemented or replaced by the use ofpositive pressure from the opposite side of the web to blow the web ontothe next fabric in addition to or as a replacement for sucking it ontothe next fabric with vacuum. Also, a vacuum roll or rolls can be used toreplace the vacuum shoe(s).

While supported by the throughdrying fabric, the web is final dried to aconsistency of about 94 percent or greater by the throughdryer 48 andthereafter transferred to a carrier fabric 50. The dried basesheet 52 istransported to the reel 54 using carrier fabric 50 and an optionalcarrier fabric 56. An optional pressurized turning roll 58 can be usedto facilitate transfer of the web from carrier fabric 50 to fabric 56.Suitable carrier fabrics for this purpose are Albany International 84Mor 94M and Asten 959 or 937, all of which are relatively smooth fabricshaving a fine pattern. Although not shown, reel calendering orsubsequent off-line calendering can be used to improve the smoothnessand softness of the basesheet.

In one embodiment, the reel 54 shown in FIG. 2 can run at a speed slowerthan the fabric 56 in a rush transfer process for building crepe intothe paper web 52. For instance, the relative speed difference betweenthe reel and the fabric can be from about 5% to about 25% and,particularly from about 12% to about 14%. Rush transfer at the reel canoccur either alone or in conjunction with a rush transfer processupstream, such as between the forming fabric and the transfer fabric.

In one embodiment, the paper web 52 is a textured web which has beendried in a three-dimensional state such that the hydrogen bonds joiningfibers were substantially formed while the web was not in a flat, planarstate. For instance, the web can be formed while the web is on a highlytextured throughdrying fabric or other three-dimensional substrate.Processes for producing uncreped throughdried fabrics are, for instance,disclosed in U.S. Pat. No. 5,672,248 to Wendt, et al.; U.S. Pat. No.5,656,132 to Farrington, et al.; U.S. Pat. No. 6,120,642 to Lindsay andBurazin; U.S. Pat. No. 6,096,169 to Hermans, et al.; U.S. Pat. No.6,197,154 to Chen, et al.; and U.S. Pat. No. 6,143,135 to Hada, et al.,all of which are herein incorporated by reference in their entireties.

As mentioned above, uncreped through-air dried paper webs made accordingto the process illustrated in FIG. 2 provide various advantages in theprocess of the present invention. It should be understood, however, thatother types of paper webs can be used in the present invention. Forexample, in an alternative embodiment, a wet creped paper web can beutilized.

For example, referring to FIG. 3, one embodiment of a papermakingmachine is illustrated capable of forming a paper web for use in theprocess of the present invention. As shown, in this embodiment, a headbox 60 emits an aqueous suspension of fibers onto a forming fabric 62which is supported and driven by a plurality of guide rolls 64. A vacuumbox 66 is disposed beneath forming fabric 62 and is adapted to removewater from the fiber furnish to assist in forming a web. From formingfabric 62, a formed web 68 is transferred to a second fabric 70, whichmay be either a wire or a felt. Fabric 70 is supported for movementaround a continuous path by a plurality of guide rolls 72. Also includedis a pick up roll 74 designed to facilitate transfer of web 68 fromfabric 62 to fabric 70.

From fabric 70, web 68, in this embodiment, is transferred to thesurface of a rotatable heated dryer drum 76, such as a Yankee dryer. Web68 is lightly pressed into engagement with the surface of dryer drum 76to which it adheres, due to its moisture content and its preference forthe smoother of the two surfaces. In some cases, however, an adhesivecan be applied over the web surface or drum surface for facilitatingattachment of the web to the drum.

As web 68 is carried through a portion of the rotational path of thedryer surface, heat is imparted to the web causing most of the moisturecontained within the web to be evaporated. Web 68 is then removed fromdryer drum 76 by a creping blade 78. Although optional, creping web 78as it is formed further reduces internal bonding within the web andincreases softness.

Once the paper web is formed, a bonding material is applied to at leastone side of the web and at least one side of the web is then creped. Ingeneral, for most applications, the paper web will only be creped on oneside after the bonding material is applied. It should be understood,however, that in some situations it may be desirable to crepe both sidesof the web. Referring to FIG. 4, one embodiment of a system that may beused to apply bonding materials to the paper web and to crepe one sideof the web is illustrated. The embodiment shown in FIG. 4 can be anin-line or off-line process. As shown, paper web 80 made according tothe process illustrated in FIG. 2 or FIG. 3 or according to a similarprocess, is passed through a first bonding agent application stationgenerally 82. Station 82 includes a nip formed by a smooth rubber pressroll 84 and a patterned rotogravure roll 86. Rotogravure roll 86 is incommunication with a reservoir 88 containing a first bonding material90. Rotogravure roll 86 applies the bonding material 90 to one side ofweb 80 in a preselected pattern.

Web 80 is then contacted with a heated roll 92 after passing a roll 94.The heated roll 92 is for partially drying the web. The heated roll 92can be heated to a temperature, for instance, up to about 250° F. andparticularly from about 180° F. to about 220° F. In general, the web canbe heated to a temperature sufficient to dry the web and evaporate anywater.

It should be understood, that the besides the heated roll 92, anysuitable heating device can be used to dry the web. For example, in analternative embodiment, the web can be placed in communication with aninfra-red heater in order to dry the web. Besides using a heated roll oran infra-red heater, other heating devices can include, for instance,any suitable convective oven or microwave oven.

From the heated roll 92, the web 80 can be advanced by pull rolls 96 toa second bonding material application station generally 98. Station 98includes a transfer roll 100 in contact with a rotogravure roll 102,which is in communication with a reservoir 104 containing a secondbonding material 106. Similar to station 82, second bonding material 106is applied to the opposite side of web 80 in a preselected pattern. Oncethe second bonding material is applied, web 80 is adhered to a crepingroll 108 by a press roll 110. Web 80 is carried on the surface of thecreping drum 108 for a distance and then removed therefrom by the actionof a creping blade 112. The creping blade 112 performs a controlledpattern creping operation on the second side of the paper web.

In accordance with the present invention, the second bonding material106 is selected such that the web 80 can be creped from the creping drum108 while the creping drum is at a relatively low temperature. Forexample, in accordance with the present invention, the creping drum 108can be maintained at a temperature of less than 200° F., andparticularly less than 150° F. In one embodiment, for example, thecreping drum 108 can be at ambient temperatures.

Since creping is accomplished at relatively low temperatures, thecreping drum 108 can have various constructions. For example, in oneembodiment, the creping drum can be a Yankee dryer that is not heated oronly heated to a relatively low temperature. Alternatively, however, thecreping drum can be a roll having a cast iron surface. The diameter ofthe creping drum can vary and is generally not critical.

Once creped, paper web 80, in this embodiment, is pulled through adrying station 114. Drying station 114 can include any form of a heatingunit, such as an oven energized by infrared heat, microwave energy, hotair or the like. Drying station 114 may be necessary in someapplications to dry the web and/or cure the bonding materials. Dependingupon the bonding materials selected, however, in other applicationsdrying station 114 may not be needed.

The amount that the paper web is heated within the drying station 114can depend upon the particular bonding materials used, the amount ofbonding materials applied to the web, and the type of web used. In someapplications, for instance, the paper web can be heated using a gasstream such as air at a temperature of about 510° F. in order to curethe bonding materials. When using low cure temperature bondingmaterials, on the other hand, the gas can be at a temperature lower thanabout 270° F. and particularly lower than about 250° F. In analternative embodiment, the drying station 114 is not used to cure thebonding material applied to the web. Instead, the drying station 114 isused to dry the web and to drive off any water present in the web. Inthis embodiment, the web can be heated to temperatures sufficient toevaporate water, such as to a temperature of from about 200° F. to about250° F.

Once passed through drying station 114, web 80 can be wound into a rollof material 116.

In one embodiment of the present invention, a low temperature curebonding material can be used that is believed to further cure over time.For example, it has been discovered by the present inventor that whenusing some types of bonding materials, the wet strength of the treatedpaper web increases over time. The increase in wet strength can bepermanent or temporary. For example, increases in wet strength have beenfound to occur over 1 day intervals and 3 day intervals.

More specifically, particular bonding materials can be chosen that whenapplied to a web in accordance with the present invention, the wetstrength of the paper product can increase by at least 25% in the crossmachine direction 72 hours after application when the paper product isstored at ambient temperatures. More particularly, the wet strength ofthe web can increase by at least 30%, and more particularly can increaseby at least 35% over a 72 hour period. Further, these increases in wetstrength can occur in shorter intervals of time, such as after 48 hoursor after 24 hours.

The bonding materials applied to each side of the paper web are selectedfor not only assisting in creping the web but also for adding drystrength, wet strength, stretchability, and tear resistance to thepaper. Particular bonding materials that may be used in the presentinvention include latex compositions, such as acrylates, vinyl acetates,vinyl chlorides and methacrylates. Some water-soluble bonding materialsmay also be used including polyacrylamides, polyvinyl alcohols andcellulose derivatives such as carboxymethyl cellulose. In oneembodiment, the bonding materials used in the process of the presentinvention comprise an ethylene vinyl acetate copolymer. In particular,the ethylene vinyl acetate copolymer can be cross-linked with N-methylacrylamide groups using an acid catalyst. Suitable acid catalystsinclude ammonium chloride, citric acid and maleic acid.

In one embodiment, the bonding material 106 used in the presentinvention may have a relatively low glass transition temperature. Forexample, the glass transition temperature may be less than about 10° C.,such as less than about 0° C., or less than about −10° C. The glasstransition temperature may vary, for instance, from about 10° C. toabout −20° C. It is believed that bonding materials having lower glasstransition temperatures will have a correspondingly lower elasticmodulus. Lowering the elastic modulus of the bonding material makes thematerial softer and easier to crepe from a surface.

As described above, and in accordance with the present invention, thebonding material 106 applied to the paper web is a bonding material thatcan adhere to a creping surface at a relatively low temperature.Examples of such bonding materials are produced by Air ProductsCorporation. One particular bonding material, for instance, is AIRFLEXEN1165. AIRFLEX EN1165 is an ethylene vinyl acetate copolymer having arelatively low glass transition temperature. For instance, the glasstransition temperature of an ethylene vinyl acetate copolymer may belowered by changing the ratios of the various components.

In another embodiment, the low temperature bonding material can be abonding material as described in U.S. Pat. No. 6,117,492 to Goldstein,et al., which is incorporated herein by reference. In the '492 patent, apolymeric binder is disclosed that has been reacted with a polyaldehyde.The polyaldehyde can be a dialdehyde such as glyoxal or glutaraldehyde.The polymeric binder can also be reacted with a polyaziridine functionalcompound.

The polymeric binder itself can be formed from a variety ofethylenically unsaturated monomers. For example, the polymeric bindercan be formed by combining a vinyl acetate, a (meth)acrylic acid, anacetoacetoxyethyl (meth)ethacrylate, and a C1 to C8 alkyl (meth)acrylicester. Such a polymer can have a glass transition temperature of fromabout −5° C. to about 10° C.

In general, the first bonding material and the second bonding materialcan be different bonding materials or the same bonding material.

The bonding materials are applied to the base web as described above ina preselected pattern. In one embodiment, for instance, the bondingmaterials can be applied to the web in a reticular pattern, such thatthe pattern is interconnected forming a net-like design on the surface.

In an alternative embodiment, however, the bonding materials are appliedto the web in a pattern that represents a succession of discrete shapes.Applying the bonding material in discrete shapes, such as dots, providessufficient strength to the web without covering a substantial portion ofthe surface area of the web.

According to the present invention, the bonding materials are applied toeach side of the paper web so as to cover from about 15% to about 75% ofthe surface area of the web. More particularly, in most applications,the bonding material will cover from about 20% to about 60% of thesurface area of each side of the web. The total amount of bondingmaterial applied to each side of the web can be in the range of fromabout 4% to about 10% by weight, based upon the total weight of the web.

At the above amounts, the bonding materials can penetrate the paper webfrom about 10% to about 70% of the total thickness of the web. In mostapplications, the bonding materials should at least penetrate from about10% to about 15% of the thickness of the web.

Referring to FIG. 5, one embodiment of a pattern that can be used forapplying a bonding material to a paper web in accordance with thepresent invention is shown. As illustrated, the pattern shown in FIG. 5represents a succession of discrete dots 120. In one embodiment, forinstance, the dots can be spaced so that there are approximately fromabout 25 to about 35 dots per inch in the machine direction or thecross-machine direction. The dots can have a diameter, for example, offrom about 0.01 inches to about 0.03 inches. In one particularembodiment, the dots can have a diameter of about 0.02 inches and can bepresent in the pattern so that approximately 28 dots per inch extend ineither the machine direction or the cross-machine direction. In thisembodiment, the dots can cover from about 20% to about 30% of thesurface area of one side of the paper web and, more particularly, cancover about 25% of the surface area of the web.

Besides dots, various other discrete shapes can also be used. Forexample, as shown in FIG. 7, a pattern is illustrated in which thepattern is made up of discrete shapes that are each comprised of threeelongated hexagons. In one embodiment, the hexagons can be about 0.02inches long and can have a width of about 0.006 inches. Approximately 35to 40 groups of hexagons per inch can be spaced in the machine directionand the cross-machine direction. When using hexagons as shown in FIG. 7,the pattern can cover from about 40% to about 60% of the surface area ofone side of the web, and more particularly can cover about 50% of thesurface area of the web.

Referring to FIG. 6, another embodiment of a pattern for applying abonding material to a paper web is shown. In this embodiment, thepattern is a reticulated grid. More specifically, the reticulatedpattern is in the shape of diamonds. When used, a reticulated patternmay provide more strength to the web in comparison to patterns that aremade up on a succession of discrete shapes.

In one particular embodiment of the present invention especially wellsuited to constructing single ply products, a first bonding material isapplied to a paper web according to the pattern shown in FIG. 5. Asecond bonding material, on the other hand, is applied to a second sideof the paper web according to the pattern illustrated in FIG. 7. Thesecond bonding material is applied to a greater amount of the surfacearea than the first bonding material. For example, the first bondingmaterial can be applied according to the pattern shown in FIG. 5 and cancover approximately 25% of the surface area of the first side of theweb. The second bonding material, however, is applied according to thepattern shown in FIG. 7 and covers approximately 50% of the surface areaof the second side of the web. Through this process, a paper product isformed having enhanced overall properties.

The process that is used to apply the bonding materials to the paper webin accordance with the present invention can vary. For example, variousprinting methods can be used to print the latex bonding materials ontothe base sheet depending upon the particular application. Such printingmethods can include direct gravure printing using two separate gravuresfor each side, offset gravure printing using duplex printing (both sidesprinted simultaneously) or station-to-station printing (consecutiveprinting of each side in one pass). In another embodiment, a combinationof offset and direct gravure printing can be used. In still anotherembodiment, flexographic printing using either duplex orstation-to-station printing can also be utilized to apply the bondingmaterials.

According to the process of the current invention, numerous anddifferent paper products can be formed. For instance, the paper productsmay be single-ply wiper products. The products can be, for instance,facial tissues, bath tissues, paper towels, napkins, industrial wipers,and the like. As stated above, the basis weight can range anywhere fromabout 15 gsm to about 110 gsm. In one particular embodiment, the presentinvention is directed to the production of a single ply paper towelproduct having a basis weight of from about 35 gsm to about 70 gsm.

Of particular advantage, the present inventor has discovered that thebulk characteristics of paper products made according to the presentinvention are improved in comparison to many conventional products. Forexample, many conventional products, such as many print creped products,have a bulk less than about 10 cubic centimeters per gram (cc/g). Paperproducts made in accordance to the present invention, however, may havea bulk greater than 10 cc/g. For example, in one embodiment, the bulk ofpaper products made in according to the present invention can be greaterthan about 11 cc/g, such as greater than about 12 cc/g.

In an alternative embodiment, paper webs made according to the presentinvention can be incorporated into multiple ply products. For instance,in one embodiment, a paper web made according to the present inventioncan be attached to one or more other paper webs for forming a wipingproduct having desired characteristics. The other webs laminated to thepaper web of the present invention can be, for instance, a wet-crepedweb, a calendered web, an embossed web, a through-air dried web, acreped through-air dried web, an uncreped through-air dried web, anairlaid web, and the like.

In one embodiment, when incorporating a paper web made according to thepresent invention into a multiple ply product, it may be desirable toonly apply a bonding material to one side of the paper web and tothereafter crepe the treated side of the web. The creped side of the webis then used to form an exterior surface of a multiple ply product. Theuntreated and uncreped side of the web, on the other hand, is attachedby any suitable means to one or more plies.

For example, referring to FIG. 8, one embodiment of a process forapplying a bonding material to only one side of a paper web inaccordance with the present invention is shown. The process illustratedin FIG. 8 is similar to the process shown in FIG. 4. In this regard,like reference numerals have been used to indicate similar elements.

As shown, a web 80 is advanced to a bonding material application stationgenerally 98. Station 98 includes a transfer roll 100 in contact with arotogravure roll 102, which is in communication with a reservoir 104containing a bonding material 106. At station 98, the bonding material106 is applied to one side of the web 80 in a preselected pattern.

Once the bonding material is applied, web 80 is adhered to a crepingroll 108 by a press roll 110. Web 80 is carried on the surface of thecreping drum 108 for a distance and then removed therefrom by the actionof a creping blade 112. The creping blade 112 performs a controlledpattern creping operation on the treated side of the web.

As described above, the bonding material 106 is selected such that theweb 80 can be creped from the creping drum 108 while the creping drum isat a relatively low temperature.

From the creping drum 108, the paper web 80 is fed through a dryingstation 114 which dries and/or cures the bonding material 106. The web80 is then wound into a roll 116 for use in forming multiple plyproducts.

When only treating one side of the paper web 80 with a bonding material,in one embodiment, it may be desirable to apply the bonding materialaccording to a pattern that covers greater than about 40% of the surfacearea of one side of the web. For instance, the pattern may cover fromabout 40% to about 60% of the surface area of one side of the web. Inone particular example, for instance, the bonding material can beapplied according to the pattern shown in FIG. 7.

In one specific embodiment of the present invention, a two-ply productis formed from a first paper web and a second paper web in which bothpaper webs are generally made according to the process shown in FIG. 8.For instance, a first paper web made according to the present inventioncan be attached to a second paper web made according to the presentinvention in a manner such that the creped sides of the webs form theexterior surfaces of the resulting product. The creped surfacesare-generally softer and smoother creating a two-ply product havingimproved overall characteristics.

The manner in which the first paper web is laminated to the second paperweb may vary depending upon the particular application and desiredcharacteristics. In some applications, a binder material, such as anadhesive or binder fibers, is applied to one or both webs to join thewebs together. The adhesive can be, for instance, a latex adhesive, astarch-based adhesive, an acetate such as an ethylene vinyl acetateadhesive, a polyvinyl alcohol adhesive, and the like. It should beunderstood, however, that other binder materials, such as thermoplasticfilms and fibers can also be used to join the webs. The binder materialmay be spread evenly over the surfaces of the web in order to securelyattach the webs together or may be applied at selected locations.

In one embodiment, one or both of the webs may be calendered or embossedprior to or after adhesively attaching the webs together. If embossed,the webs can be nested or in a pin-to-pin arrangement.

Referring to FIG. 9, one embodiment of a process for laminating a firstpaper web 80 to a second paper web 180 is shown. In this embodiment,paper web 80 is intended to represent a paper web made according to theprocess shown in FIG. 8. Paper web 180, on the other hand, can be anysuitable paper web. In one particular embodiment, however, the paper web180 is generally the same in construction as the first paper web 80.

As shown, the first paper web 80 and the second paper web 180 are fedinto a nip defined by a pair of calender rolls 150 and 152. The paperwebs are guided into the nip by a pair of rollers 154 and 156. Prior toentering the nip, one or both of the webs can be contacted with anadhesive being emitted by an adhesive spray nozzle 160. The adhesiveattaches the two webs together. Ultimately, a laminated product 162 isformed.

In an alternative embodiment, instead of calender rolls 150 and 152, theprocess shown in FIG. 9 can include embossing rolls which not only pressthe webs together but also emboss the webs as they are joined. Theembossing rolls can include embossing knuckles that can be in an offsetrelationship or in a pin-to-pin relationship.

In one particular embodiment of the present invention, as discussedabove, paper web 80 and paper web 180 can both be made according to theprocess shown in FIG. 8. In this embodiment, the creped side of each webcan form the exterior surfaces of the resulting product 162. When webs80 and 180 are uncreped through-air dried webs, the creped side of theweb can also be the air side as described above. Consequently, theuncreped and untreated, fabric side of the webs are joined togetherduring formation of the product 162. In this arrangement, a paperproduct is formed having soft and smooth exterior surfaces.

Referring to FIG. 10, another embodiment of a process for laminating thefirst paper web 80 to a second paper web 280 is shown. In thisembodiment, the first paper web 80 is embossed by an embossing roll 200and fed through an adhesive application station 202. The adhesiveapplication station is an offset printer in which a first roller 204 isdipped into an adhesive. The adhesive is transferred to a second roller206 and then to a third roller 208 before being applied to the paper web80. It should be understood, however, that the adhesive can be appliedto the web in other ways, such as by spraying.

Once the adhesive is applied to the paper web 80, the paper web isjoined to the second paper web 280 by a pair of press rollers 210 and212. If desired, press rollers 210 and 212 can also be calender rolls.Once the webs are joined together, a laminate 214 is formed.

Besides the above methods for joining the webs, it should be understoodthat any suitable manner for laminating the two webs together can beused in the present invention. Further, it should also be understoodthat the laminate product of the present invention can include more thantwo plies if desired.

When using an adhesive as shown in FIGS. 9 and 10, the adhesive can beapplied evenly over one or more surfaces of the plies or can be appliedat selected locations. Further, besides the use of adhesives, it shouldbe understood that other bonding materials can be used. For example,binder fibers can be applied in between the plies for bonding the pliestogether. When using binder fibers, the two plies are heated andthermally bonded together by melting at least a portion of the binderfibers.

In still another embodiment, the plies may be mechanically attachedtogether using, for instance, crimped fibers. Crimped fibers on onesurface of the first web can, for instance, entangle with crimped fiberslocated on an opposing surface of the second web.

The present invention may be better understood with reference to thefollowing examples.

EXAMPLE 1

To illustrate the properties of a wiping product made in accordance withthe present invention, an uncreped through-air dried (UCTAD) base webwas treated with a bonding material according to the teachings of thepresent invention and the web was then subjected to various standardizedtests. The UCTAD base web was formed in a process similar to the methodshown in FIG. 2. In this particular example, the base web was made froma stratified fiber furnish containing a center layer of fiberspositioned between two outer layers of fibers. Both outer layers of theUCTAD base web contained 100% northern softwood Kraft pulp and up to 6kg/MT of TQ1003 debonder obtained from the Hercules Corporation. Thecenter layer contained 50% softwood Kraft pulp and 50% BCTMP pulp and upto 6 kg/MT of TQ1003 debonder.

The first side of the web was printed with a bonding material usingdirect rotogravure printing. Then, the printed web passed over a heatedroll to evaporate water. Next, the second side of the web was printedwith the bonding material using a second rotogravure printer. The webwas then pressed against and doctored off a rotating drum, which had asurface temperature of 125 degrees Fahrenheit. Finally, the sheet wasdried and the bonding material cured and wound into a roll.

The bonding material in this particular example included AirFlex EN1165,which was obtained from Air Products, Inc. of Allentown, Pa. Air FlexEN1165 contains an ethylene vinyl acetate copolymer.

The bonding material containing, AirFlex EN1165, had the followingformulation:

TABLE 1 EN1165 (52% solids, nominal) 10500 g Nalco 94PA093 Defoamer 54 g(100% solids) Water 3000 g Catalyst (Ammonium Chloride) 545 g (10%solids) Thickener (Hercules) (2% solids) 1100 g Natrosol 250MR

The samples were then subjected to standardized tests for wet and drytensile strength and stretch. The term “elongation” refers to theincrease in length of a sample during testing. The tensile strength andthe percent stretch of samples were determined in the machine direction(MD) and in the cross machine direction (CD). The results are expressedin pounds or grams to break and percent stretch before breakage. Highernumbers indicate a stronger, more stretchable fabric.

During these test, strength was determined using a geometric meantensile strength test (GMT). The size of the samples tested were 3inches in width. During the test, each end of a sample was placed in anopposing clamp. The clamps held the material in the same plane, usuallyvertically, separated by 4 inches and moved apart at a ten inch perminute rate of extension. The clamps moved apart until breakage occurredin order to measure the tensile strength of the sample. The geometricmean tensile strength was then calculated by taking the square root ofthe machine-direction tensile strength of the sample multiplied by thecross-direction tensile strength of the sample.

Tensile strength tests and elongation tests were performed on a SYNERGYtester available from MTS Systems, Corp. located in Eden Prairie, Minn.Results are reported in grams or in grams per inch width of sample.

Wet tensile strength was measured in the same manner as dry strengthexcept that the sample was wetted prior to testing. Specifically, inorder to wet the sample, a 3″×5″ tray is filled with distilled ordeionized water at a temperature of 23±2° C. The water is added to thetray to an approximate 1-centimeter depth.

A 3M “Scotch-Brite” general purpose scrubbing pad is then cut todimensions of 2.5″ long×4″ wide. A piece of masking tape approximately5″ long is placed along one of the 4″ edges of the pad. The masking tapeis used to hold the scrubbing pad.

The scrubbing pad is then placed into the water with the taped endfacing up. The pad remains in the water at all times until testing iscompleted. The sample to be tested is placed on blotter paper thatconforms TAPPI T205. The scrubbing pad is removed from the water bathand taped lightly three times on a screen associated with the wettingpan. The scrubbing pad is then gently placed on the sample parallel tothe width of the sample in the approximate center. The scrubbing pad isheld in place for approximately 1 second. The sample is then immediatelyput into the tensile tester and tested.

To calculate the wet/dry tensile strength ratio, the wet tensilestrength value was divided by the dry tensile strength value.

All samples were tested in both the machine direction and the crossdirection to obtain percent stretch value.

To calculate the percent elongation, the length of the sample at restwas divided by the maximum length of the sample prior to breakage. Allsamples were tested in both the machine direction and the crossdirection.

As shown below, the basis weight, caliper, and bulk of the samples werealso measured. To measure bulk, a thickness measurement was firstconducted on a stack of 10 sheets at a load of 2 kPa using a 56.4 mmdiameter circular platen to apply the load. The sheets rested beneaththe flat platen and above a flat surface parallel to the platen. Thetester senses displacement of the platen caused by the presence of thesheets. The tester may be, for instance, an Emveco 200-A tissue calipertester. Bulk is calculated by dividing the thickness of 10 sheets by 10to get the per sheet stack caliper. This value is then divided by the asis basis weight to arrive at the stack bulk.

The results of the tests obtained when the AirFlex EN1165 bonding agentwas used are shown below:

TABLE 2 GMT (grams/76 mm) 1387 MD Tensile (grams/76 mm) 1602 MD Stretch(%) 26.2 CD Tensile (grams/76 mm) 1201 CD Stretch (%) 14.5 CD WetTensile 879.4 CD Wet/Dry Ratio 70.9% Basis Weight - as is (g/m²) 64.77Basis Weight - bone dry (g/m²) 60.73 Caliper 1-sheet (inches) 0.0330Caliper 10-sheet (inches) 0.295 Stack Bulk (cc/g) 11.56

EXAMPLE 2

In this example, a wiping product was formed as described in Example 1using a bonding agent, namely AirFlex 426, obtained from Air Products,Inc. of Allentown, Pa. Air Flex 426 is a polyvinyl acetate emulsion. Thebonding material had the following formulation:

TABLE 3 AirFlex 426 (63% solids, nominal) 8000 g Nalco 94PA093 Defoamer50 g (100% solids) Water 3920 g Experimental Additive 16055-94A 1250 g(Air Products) Thickener (Hercules) (2% solids) 1050 g Natrosol 250MR

Standardized tests for stretch and wet/dry tensile strength wereconducted, as described in Example 1, on a UCTAD base web printed withAirFlex A426 bonding agent in accordance to the present invention. Thefollowing results were obtained:

TABLE 4 GMT (grams/76 mm) 1355 MD Tensile (grams/76 mm) 1628 MD Stretch(%) 29.2 CD Tensile (grams/76 mm) 1128 CD Stretch (%) 11.5 CD WetTensile 700.7 CD Wet/Dry Ratio 62.1% Basis Weight - as is (g/m²) 67.26Basis Weight - bone dry (g/m²) 62.58 Caliper 1-sheet (inches) 0.0369Caliper 10-sheet (inches) 0.330 Stack Bulk (cc/g) 12.46

In this example, the CD wet/dry ratio was tested soon after the productwas formed and then retested 3 weeks later. Initially, the paper web wasfound to have a wet/dry ratio of approximately 30%. The wet/dry ratiothen increased to approximately 62% over a 3 week time period. Althoughunknown, it is believed that the bonding material continued to cure overthe 3 week storage period.

These and other modifications and variations to the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present invention, which ismore particularly set forth in the appended claims. In addition, itshould be understood that aspects of the various embodiments may beinterchanged both in whole or in part. Furthermore, those of ordinaryskill in the art will appreciate that the foregoing description is byway of example only, and is not intended to limit the invention sofurther described in such appended claims.

1. A method for producing a paper product comprising the steps of: providing a first paper web comprising softwood fibers, said paper web having a first side and a second side; applying a first bonding material to said first side of said web in a preselected pattern and adhering said first side of said web to a creping surface, said creping surface being at a temperature of less than about 200° F., wherein the first bonding material comprises a polyaldehyde; creping said first side of said web from said creping surface; and laminating the second side of the first paper web to a second paper web.
 2. A method as defined in claim 1, wherein the second paper web is made in the same manner as the first paper web, the second paper web including a first side and a second side, the first side defining a creped surface, the second side of the second paper web being laminated to the second side of the first paper web.
 3. A method as defined in claim 1, wherein the second paper web comprises softwood fibers and has a first side and a second side, the second paper web being formed by: applying the first bonding material to the first side of the second paper web in a preselected pattern and adhering the first side of the second web to a creping surface, the creping surface being at a temperature of less than about 200° F.; and creping the first side of the second paper web from the creping surface; and wherein the second side of the second paper web is laminated to the second side of the first paper web.
 4. A method as defined in claim 1, wherein the first paper web is laminated to the second paper web by applying an adhesive in between the two webs.
 5. A method as defined in claim 1, further comprising the step of calendering the first paper web and the second paper web after the webs have been laminated together.
 6. A method as defined in claim 1, further comprising the step of embossing the first paper web and the second paper web after the webs have been laminated together.
 7. A method as defined in claim 1, the first paper web has a basis weight of from about 20 gsm to about 40 gsm.
 8. A method as defined in claim 1, wherein the first paper web further comprises high-yield fibers.
 9. A method as defined in claim 8, wherein the first paper web contains high-yield fibers in an amount from about 2% to about 40% by weight.
 10. A method as defined in claim 1, wherein the first paper web includes a middle layer comprising softwood fibers, a first outer layer comprising softwood fibers and a second outer layer also comprising softwood fibers.
 11. A method as defined in claim 1, wherein the creping surface is at a temperature of less than about 125° F.
 12. A method as defined in claim 1, wherein the creping surface is at ambient temperature.
 13. A method as defined in claim 1, wherein the first paper web that is provided comprises an uncreped through-air dried web.
 14. A method as defined in claim 13, wherein the uncreped through-air dried web has undergone rush transfer between a first web conveying device and a second web conveying device prior to applying said bonding material, said web conveying devices having a speed differential of from about 5% to about 45%.
 15. A method as defined in claim 1, wherein said first paper web further comprises a debonding agent, said debonding agent being added to said first web in an amount from about 1 kg/metric tonne to about 10 kg/metric tonne based on the total weight of fibers contained in said first web, said debonding agent inhibiting the fibers in said web from bonding together during formation of said paper web.
 16. A method as defined in claim 1, wherein said first bonding material is applied to said first side of said first paper web in a pattern that covers from about 40% to about 60% of the surface area of said first side.
 17. A method as defined in claim 16, wherein said first bonding material is applied to said first paper web in an amount of from about 4% to about 10% by weight of said paper web.
 18. A method as defined in claim 16, wherein said first bonding material is applied to said first paper web in a preselected pattern that comprises a succession of discrete shapes.
 19. A method as defined in claim 1, wherein the first bonding material is selected such that the wet strength of the first paper web increases by at least 25% in the cross machine direction 72 hours after application of the bonding material when the paper web is stored at ambient temperatures.
 20. A method as defined in claim 1, wherein the first bonding material has a glass transition temperature of less than about 10° C.
 21. A method as defined in claim 1, wherein the second side of the first paper web is not treated with a bonding material and is uncreped prior to being laminated to a second paper web.
 22. A method as defined in claim 1, wherein the first paper web has a bulk of greater than about 10 cc/g.
 23. A method as defined in claim 1, wherein the first paper web has a bulk of greater than about 11 cc/g.
 24. A method as defined in claim 1, wherein the first paper web has a bulk of greater than about 12 cc/g.
 25. A method as defined in claim 1, wherein the polyaldehyde comprises glyoxal.
 26. A method as defined in claim 1, wherein the polyaldehyde comprises glutaraldehyde.
 27. A method for producing a two-ply paper product comprising: providing a first paper web and a second paper web, each of the paper webs having a first side and a second side and each of the webs containing softwood fibers, the first paper web and the second paper web comprising uncreped through-air dried webs; applying a first bonding material to the first side of the first paper web and to the first side of the second paper web in a preselected pattern and adhering the first side of both of the webs to a creping surface, the creping surface being at a temperature of less than about 200° F., wherein the first bonding material comprises a polyaldehyde; creping the first side of the first paper web from a creping surface and creping the first side of the second paper web from a creping surface; and thereafter laminating the second side of the first paper web to the second side of the second paper web to form a two-ply paper product.
 28. A method as defined in claim 27, wherein the first paper web contains high-yield fibers.
 29. A method as defined in claim 27, wherein the creping surface for the first paper web and the second paper web is at a temperature of less than about 125° F.
 30. A method as defined in claim 27, wherein the first and second uncreped through-air dried webs have undergone rush transfer between a first web conveying device and a second web conveying device, said second web conveying device being downstream from said first web conveying device, said second web conveying device moving from about 5% to about 45% slower than said first web conveying device.
 31. A method as defined in claim 27, wherein the first bonding material is applied to the paper webs in a pattern that comprises a succession of discrete shapes.
 32. A method as defined in claim 27, wherein the first paper web is laminated to the second paper web by applying an adhesive in between the two webs.
 33. A method as defined in claim 27, further comprising the step of calendering the first paper web and the second paper web after the webs have been laminated together.
 34. A method as defined in claim 27, further comprising the step of embossing the first paper web and the second paper web after the webs have been laminated together.
 35. A method as defined in claim 27, wherein the two-ply product has a basis weight of from about 40 gsm to about 80 gsm.
 36. A method as defined in claim 27, wherein the uncreped through-air dried webs include an air side and a fabric side, the first side of the first paper web and the first side of the second paper web comprising the air side of the webs.
 37. A method as defined in claim 27, wherein the uncreped through-air dried webs include an air side and a fabric side, the first side of the first paper web and the first side of the second paper web comprising the fabric of the webs.
 38. A method as defined in claim 27, wherein the first bonding material has a transition temperature of less than about 10° C.
 39. A method as defined in claim 27, wherein the first bonding material has a glass transition temperature of less than about 0° C.
 40. A method as defined in claim 27, wherein the first bonding material has a glass transition temperature of less than about −10° C.
 41. A method as defined in claim 27, wherein the second side of both of the webs is uncreped and not treated with a bonding material prior to being laminated together.
 42. A method as defined in claim 27, wherein the first paper web and the second paper web each have a bulk greater than about 10 cc/g.
 43. A method as defined in claim 27, wherein the first paper web and the web each have a bulk greater than about 11 cc/g.
 44. A method as defined in claim 27, wherein the first paper web and the second paper web each have a bulk greater than about 12 cc/g.
 45. A method as defined in claim 27, wherein the polyaldehyde comprises glyoxal.
 46. A method as defined in claim 27, the wherein the polyaldehyde comprises glutaraldehyde. 